Rock drill blowing device



Dec. 26, 1933. J. c. CURTIS 1,940,846

ROCK DRILL BLOWING DEVICE Filed July 30. 1932 JOHN CrCUET/5 E9" 1INVENTOR ATTORNEY BY ghaw 1 Another object Patented Dec. 26, 1933 I1,940,846 V V noon DRILL BLOWING. DEVICE] John 0. Curtis, Cleveland,ohm,

assignor to The ClevelandRock Drill Company, Cleveland, Ohio, j

a corporation of Ohio Application uly'ao, 1932;

Serial No. 626,2 59

- Claims. (or 121-10) This invention relates broadly to rock drills, butmore particularly to a blowing device for fluid actuated rock drilloflthev tappet type;

One of the objects of theinvention is-to produce. a rock drill with ablowingl'device capable of admittingpressure fluid under full linepressure to the cutting tool for cleaning the hole being drilled. A r

of this invention isto produce a blowing devicefor rock, drill which "issimple in .design andcapable of easy, operation.

.Other' objects and advantages more ,orpless ancillary. to the foregoingand the manner in which the various objects are attained reside in thespecific construction and arrangement of the :elements peculiar to thisstructure, as will become apparent from a more complete examination ofthis specification, in the claims of which there are assembled certainspecific combinations of parts and specificconstructions indicative ofthe scope r piston chamber 11."

'valve totheforward portion of the machine, there is an enlargedpassage35i This passage i'sinconand spirit of the invention. I v In thedrawing: Fig. l is a longitudinal view ofa rock drillem bodying theinvention. a

li'ig. 2- is a cross sectional viewtaken in :a plane indicated by line2+2in Fig.1.

Fig. 3 is a view similar to Fig. 2 takenin a plane indicated by line 3-3in Fig. 1.

The embodiment. of the invention chosenfor 'thepurpose of illustrationcomprises a rock drill having a cylinder 10 formed with a pistonchamberv l1. .Reciprocably ,mounted within .the "chamber 11, there isapiston 12 formed with a fluted; extension 13, which is capable ofslidable but ,nonerotatable engagement within the fluted bore 14 of achuck 15.,This chuck is rotatably mounted-within afront housing 16,attached to 1 the cylinder 10 in anysuitable manner. Secured 'withinthe-front end'of the chuck in'pressed fit relation therewith, there isachuck bushing 17 conveniently machined to slidably receive the shank'l8of a-working-impl'ement.

' The working implement is provided with a centrally disposed orifice 19through which pressure 'fluid may be admitted to the cuttingedgeof the1implementjorcleaning the drilled hole. In terposed "betweentlie end .ofthe piston fluted portion 13 andthe end ofthei'shank 18,,ther'e is,a'tappet 20 ,sli'clably mounted within a tappet chanibe'rZl fluidtightengagement with the wall thereof.

The :tappet '20 is formed of differential diameters,

providing at their intersection, a tappet seat; 22

capable of engagement with thechuck:-15.to limit -,its:rearward' travel.-'I-his.tappet is also provided 27 there is provided an enlargedpas'sage 3lio'pen- .thetappetchamber ZfLthlOllgh an annular recess 38formed on the external wall of the chuckl5, [and through a plurality oi-radially disposed paswith a centrally disposed orifice 23 somewhat.larger than the orifice l9.

' Secured'within the rear end of the-cylinder 10,

there is a valve block 24, within which there is 'reciprocably mounted afluid actuated valver25 for so controlling the admission of the pressure'into'the piston chamber 11 to actuate the piston.

The machine is terminated by a backhead-;26 having, rotatablydisposedth'erein, a throttle valve 27, which is formed with a centrallylocated bore 28 into which pressure fluid, may be admitted. The throttlevalve is'also providedwi-th radiallydisposed enlarged; orifice .29,and-.re strictedport 30; Leading from the throttle valve ing intoanannular recess 32, which iszin constant communication with valve 25through a'plurality of passages 33. Capable of communication with thethrottle valve restricted port. 30,- :the'r'ei's a .passagei fi iopening'within'the rear end of the Leading from the throttle stantcommunication withr the bore ,14 of:the chuck -1-5,;through acircularspace-36 provided between the chuck 15 and its housing .16,'andthrough a plurality of radially disposed ports,37, opening. into thespace 36-and bore-14. The enlarged passage .is also in; communication:with sages 39, leading Irom' the recess 38 intojthe tappet chamber 21.

Disposed between the-backhead 26 and the qvalve' block 24, thereishawratchet mechanism comprisinga toothed ring :40 having rotatabletherein the head 41 of a rifled'stem42b The stem 421$ capable of'slidable engagement withthe fluted bore of the piston 12, and withinits head i there is disposed a plurality o'fpawls-and .plungersefiecting the rotation-0t thepiston lZ in a manner common-to tools ofthis type. i 1 r Secured within the backhead26, there is a tube 43extendinginto the orifice l9 of'the tool imple- 100 ment. This tube isadapted to carry cleaning fluid from the backheadto the cuttingdge of"the tool implement -to'cle'an the drilled hole duringthenorm'aloperation of the machine.

When the'throttle valve 27 is located to pip-"1105 sition thethrottle-valve enlarged orifice 29*in communication with enlargedpassage -31-,'pressure fluid is admitted into the valve block 24 to-becontrolled by. the fluid actuatedvalve 25'and distributed into thepiston chamber 11 to"a'ctuate the piston 12. During its reciprocation,the piston 12 will deliver its blowsto the tappet 20, which willtransmit the blows to the tool implement by the medium of its shank 18,accomplishing thereby the drilling of the hole.

When it is desired to clean the drilled hole, the throttle valve may bepositioned as illustrated in Fig. 1. In that position the admission ofthe pressure fluid into the valve block 24 is shut off. The throttlevalve enlarged orifice 29 being in communication with the enlargedpassage 35, pressure fluid will be admitted into the bore 14 through thecircular space 36 and ports 37. The

pressure fluid admitted into the bore 14 will act upon the front end ofthe piston fluted extension 13 to move the piston 12 rearwardly or awayfrom the tappet 20, thus allowing the pressure fluid to flow through thetappet orifice 23 into the orifice 19 of the tool implement and to thecutting edge of the tool to clean the hole being drilled.Simultaneouslypressure fluid is admitted into the rear end of the pistonchamber 11 to act against the piston 12 to maintain the pistonsubstantially in the position illustrated in Fig. 1. The port 34 beingsmaller than the enlarged orifice 35, the pressure within the pistonchamber 11 will be less than the pressurewithin the bore 14. However,the pressure within the piston chamber 11 will slowly increase to movethe piston 12 forwardly against the pressure exerted upon the front endof the piston stem 13. When the piston finally uncovers the exhaustpassage 44 provided through the wall of the cylinder 10, the pressurewithin the rear end of the piston chamber 11 will drop, allowing thepiston 12 to move rearwardly. Thus the piston is capable ofreciprocation but is held away from the end of the tappet to allow thepassage of the pressure fluid into the tappet orifice 23. It will benoted that during the drilling operation, when the cutting edge of thetool implement is maintained against j the work, the operator may blowthe chips away from the cutting edge of the tool by simply manipulatingthe throttle valve 27.

At the same time that the pressure fluid is admitted into the bore '14,it is also admittedinto the chamber 21 through the annular recess 38 andports 39 to act against the front face of the tappet 20, and maintainits seat 22 in engagement with the chuck 15.- At the end of the drillingoperation, when the machine is retracted from the work, the pressureinto the tappet chamber 21 willact on the end of the shank 18 to move itaway from the tappet 20, thusallowing an additional amount of pressurefluid to flow into the orifice 19 to the cutting edge of the workingimplement. The combined pressure fluid from the bore 14 and tappetchamber 21, flowing into the bottom of the drilled hole will besuflicient to aiford an eflicient blowing device. By the simplemanipulation of the throttle valve, pressure fluid may be admitted tothe cutting edge of the working implement from two diiferent sources,the pressure fluid from one of these sources being controlled by theretraction of the machine from the work.

Although the foregoing description is necessarily of a detailedcharacter, in order to completely set forth the invention, it is to beunderstood that the speciflc terminology is not intended to berestrictive or confining and it is to be further understood that variousrearrangements of parts and modification of structural detail may beresorted to without departing from as herein reciprocable therein, saidpiston having a stem extending within a member rotatably mounted withinthe front housing of said machine and capable to receive the shank of aworking implement having a bore therethrough, a tappet interposedbetween said stem and shank and capable to receive the blows of theformer and transmit them to the latter, a fluid actuated valve fordistributing the pressure fluid into said piston chamber to actuate saidpiston, a throttle valve for controlling the admission of the pressurefluid to said fluid actuated valve, passages controlled by said throttlevalve for admitting pressure fluid to both ends of said tappet, thepressure fluid admitted to one end of said tappet acting upon said stemto maintain the latter in spaced relation with the former, a borethrough said tappet for conveying pressure fluid from one end of saidtappet into the bore of said working implement when the latter is heldin engagement with said tappet, the pressure fluid from the other end ofsaid tappet being capable of flow into the bore of said workingimplement when the latter is maintained'in spaced relation with saidtappet, and means for simultaneously admitting pressure fluid into oneend of said piston chamber to prevent the complete travel of said pistonwhen pressure fluid acts on thefront end of said stem.

2. In a fluid actuated machine comprising a housing having a pistonchamber with a piston reciprocable therein, said piston having a stemextending within a member rotatably mounted within the front housing ofsaid machine and capable to receive the shank of a working implementhaving a bore therethrough, a tappet slidably mounted within said memberand interposed between said stem and shank to receive the blows its ofthe former and transmit the same to the latter,

pet at one extreme end of its travel, thepressure fluid admitted to saidrestricted area acting upon said stem to maintain the latter away fromthe former and allow the passage of pressure fluid therebetween, a borethrough saidtappet to convey said last mentioned pressure fluid into thebore of said working implement, the pressure fluid from the enlarged ofsaid areas being adapted to flow into the bore of said tool implementwhen the latter is maintained in spaced relation with said tappet, andmeans for simultaneously admitting pressure fluid into one end of saidpiston chamber to prevent the complete travel of said, piston whenpressure fluid acts on the front end of said stem. l

3..In a fluid actuated machine comprising a housing having a pistonchamber with a piston reciprocable therein, a member rotatably mountedwithin the front end of said machine andcapable to slidably receivethe'shank' of a working implement, atappet interposed between saidpiston and i said shank to transmit the blows of the former to thelatter, said tappet being maintained in engagement with said shank bythe force applied to said machine to secure said working implementagainst the work, passages for admitting pressure fluid to each end ofsaid tappet, means ter is held against the work, and means for admittingan additional amount of pressure fluid into the bore of said workingimplement from the other end of said tappet when the machine isretracted from the work.

4. In a fluid actuated machine comprising a housing having a pistonchamber with a piston reciprocable therein, a member rotatably mountedwithin the front end of said machine and capable to slidably receive theshank of a working implement, a tappet interposed between said pistonand said shank to transmit the blows of the former to the latter, saidtappet being maintained in engagement with said shank by the forceapplied to said machine to secure said working implement against thework, passages controlled by a valve for admitting pressure fluidbetween the engaging surfaces of said tappet and shank, thus exertingpressure on said shank to move it away. from said'tappet when themachine is retracted from the work, permitting thereby the admission ofsaid pressure fluid into the bore of said working implement to clean thedrilled hole.

5. In a fluid actuated machine comprising a housing having a pistonchamber with a piston reciprocable therein, a hollow drilling toolimplement having a shank slidably mounted .into the between said pistonand said shank for transmitting the, blows of the former to the latter,and means for admitting pressure fluid between the engaging surfaces ofsaid member and shank, permitting thereby the admission of pressurefluid through said hollow tool implement to clean the drilled hole. 7

JOHN C. CURTIS.

1 front end of said machine, a member interposed

